Incidence and severity of maize streak disease: The influence of tillage, fertilizer application and maize variety

Maize streak disease (MSD) is one of the most destructive diseases of maize (Zea mays L.) estimated to cause a yield loss of about 20% in Ghana. Field experiment was conducted at Nkwanta in the Volta Region of Ghana during the cropping seasons of 2015 to assess the effects of tillage practices, fertilizer application and maize variety on the incidence and severity of MSD. The MSD severity was assessed using 1 to 5 visual scale (1=no symptom and 5= very severe symptom). The relationship between total N, available P and exchangeable K contents of soils and maize leaves sampled at silking stage and MSD incidence and severity were elucidated with Pearson correlation coefficients. Although symptoms were observed in both fertilized and non-fertilized plants, fertilizer addition effectively reduced the MSD impact on growth and yield. Incidence and severity of MSD under no-tillage system were significantly lower than under conventional tillage. Severe MSD, particularly, of plants on the plots with no added nutrients led to stunted growth and reduced grain yield. The severity of MSD correlated positively with maize leaf N content, while increasing leaf K content resulted in reduced MSD severity. It can therefore be concluded that tillage and plant nutrition affect the severity of MSD in tropical soil.   Key words: Zea mays, grain yield, inorganic fertilizer, maize streak disease, maize varieties, tillage.